Using SBS Adapters Instead of Single Board Computers

SBS Technologies Adapters Instead of Single Board Computers

Single Board Computers (SBCs) are widely accepted and used by system designers worldwide to provide specialized processing and I/O capabilities; however, SBCs are not the only solution for many applications. A VMEbus bus adapter from SBS Bit 3 Operations is a viable alternative to a SBC and often the best choice. In most cases, when an adapter can take the place of a SBC, the adapter implementation:

• Has a lower total system cost;
• Allows easier system upgrades and migration to different platforms;
• Enhances performance;
• Is more convenient;
• Provides extremely low latency and CPU overhead; and
• Speeds development time and reduces time to market.

Each SBS Bit 3 VMEbus adapter feature set was carefully designed and implemented to address the rigorous requirements of VMEbus connectivity:

Advantages of Using a Bus Adapter Instead of an SBC

Lower total system cost

• Use economical standard PCs and workstations. Install the adapter in an existing desktop system for maximum cost savings.

• Take advantage of desktop upgrades while using the same adapter. Desktop systems are generally upgraded with new technology even if not used with an adapter. By using the desktop system used for day-to-day functions, the cost of upgrading both the desktop system and the SBC is eliminated.

• Use a wealth of available, user-friendly, off-the-shelf software.

• Support and service are readily available worldwide from major PC, workstation and operating system manufacturers.

• Economical peripherals and I/O functions can be used instead of expensive VMEbus alternatives; for example, disk controllers and serial ports are less costly for PCs than VMEbus versions.

• Retain use of standard VMEbus I/O that you know and are comfortable using.

• Substantially reduce training time and expense by using a familiar operating system and development tools with which you are already proficient.

More options

Workstations/PCs offer appreciably more hardware options than SBCs. Options available on a SBC are limited by the physical size of the card.

Performance

Satisfy real-time, deterministic interconnection requirements. Memory mapped transfers are handled by normal system virtual memory and system bus arbitration logic. No software protocol overhead is used. The VMEbus supports priority or round-robin arbitration that allows the system architect to control how long a bus master waits to be granted the bus. For systems requiring low latency, the DMA engine provides a pause mode for more frequent rearbitration.

Easily upgrade to the newest systems and processors

• Take advantage of the latest processor technology as soon as it is available. New processors for PCs and workstations are available before SBC versions.

• Swapping systems is easy; simply remove the adapter card from the older system and re-install it in a faster, more powerful computer.

• Use the same software you are conversant with even if the host operating system is changed.

Extremely low system latency and low CPU overhead

Bus adapters provide point-to-point connectivity between two physically separate bus systems at the hardware level; no protocol is required. Consequently, system latency and CPU overhead are extremely low.

Power up or down the VMEbus chassis without affecting the whole system

Each system's bus operates independently; the two buses are linked only when one system sends data to the other system. Consequently, the VMEbus chassis can be powered up or down without affecting CPU operation at the remote end of the adapter cable.

Easy migration to different platforms

As requirements change, your current platform may not provide the necessary capabilities. With an adapter you can quickly and easily migrate from one platform to another. SBS Bit 3 offers a variety of adapters that connect a VMEbus to a PCI bus, ISA bus, EISA bus, MULTIBUS, SBus, Q22-bus, or GIO bus. In addition, Support Software available for several adapters includes the Mirror API that is designed to facilitate portability.

Convenience

• Workstations/PCs are easier to work with, upgrade, and to swap out completely than SBCs. Simply remove the adapter card from the workstation or PC and re-install it in your new system.

• Physically separate the CPU and I/O. In many installations, the CPU and I/O need to be physically separated. If data is gathered in a harsh or hazardous environment, processing must take place in a safer environment. In many manufacturing installations, it is desirable to have I/O on the production floor and a workstation for processing in an office environment. Adapters that use copper conductor cable allow system separation up to 7.5 meters. For environments requiring greater separation, bus adapters with fiber-optic options or built-in fiber-optic capabilities allow CPU and I/O system separation up to 2000 meters.

• Easily add a friendly Graphical User Interface (GUI) to complete an embedded system. An adapter and a standard PC or workstation is the ideal combination for providing an intuitive, easy-to-use environment for your system operator.

Enhanced normal system performance

Each adapter card operates independently. The timing of the two buses is linked only when a memory or I/O reference is made to an address on one bus that translates to a reference on the other bus. Therefore, the adapter enhances, never detracts from normal system performance.

Easy customer specific application development

SBS Bit 3 adapters employ advanced memory mapping techniques that allow remote bus address space to be mapped to an unused address space on the host system. The mapped remote memory appears as local memory to the host system. For example, remote memory, when memory mapped, functions as if it were local memory allowing the use of all normal C language constructs. Memory mapped resources can be dereferenced using simple C language pointers.

Memory mapping also controls random access (PIO transfers) to remote bus RAM, optional Dual Port RAM, and remote bus I/O. For most SBS Bit 3 adapters, this capability is bi-directional.

Frees the CPU for other functions and maximizes processor efficiency

Many SBS Bit 3 adapter models provide an internal DMA controller for high-performance direct memory-to-memory data transfers between buses. DMA transfers require minimal processor attention. Two DMA modes are supported: Controller Mode DMA and Slave Mode DMA.

Host system can consider VMEbus system's changed. peripherals as its own

Slave Mode DMA enables a VMEbus DMA controller card to transparently send data using a burst mode access through the adapter into the other bus's memory. For example, a VMEbus DMA controller such as a disk controller or tape controller can transmit its data from the VMEbus directly to the host system's memory under control of the VMEbus DMA Controller.

Access to special VMEbus I/O cards

Retain use of legacy VMEbus cards and special VMEbus I/O cards after changing the VMEbus system.

Portability of application software among most major operating systems

SBS Bit 3 provides device drivers for many adapter models. These drivers are designed so that application software in which they are incorporated can be easily ported to other operating systems.

Conforms to VMEbus specifications

VMEbus adapter cards comply with IEEE 1014C specifications.

The following examples depict how a bus adapter can be used to replace a SBC. In each example, Diagram A shows a system using a SBC; Diagram B shows the system with the SBC replaced by a SBS Bit 3 bus adapter.

• Example 1:

Benefits and cost savings:

• Total system is less expensive than a SBC solution.
• Eliminates a SBC.
• Convenience: a workstation is easier and more convenient to work with than a SBC.
• Abundant options.
• Can use off-the-shelf, feature-rich software.
• Readily available support from workstation vendor.

• Enhanced performance.
• Easy upgrades.
• Extremely low system latency and CPU overhead.
• Ability to power-up or down the VMEbus chassis without affecting the whole system.
• Workstation can also be used to provide a GUI.

• Example 2:

• Total system is less expensive than a SBC solution.
• Eliminates an SBC that includes Ethernet capabilities.
• Convenience: a workstation is easier and more convenient to work with than a SBC.
• Abundant options.

• Can use off-the-shelf, feature-rich software.
• Readily available support from PC vendor. Enhanced performance.
• Easy upgrades.
• Extremely low system latency and CPU overhead.
• Ability to power-up or down the VMEbus chassis without affecting the whole system.

• Example 3:

• Total system is less expensive than an SBC solution.
• Eliminates three SBCs that include Ethernet capabilities.
• Eliminates three operating system licenses.
• Convenience: workstations are easier and more convenient to work with than SBCs.
• Abundant options.
• Can use off-the-shelf, feature-rich software.

• Readily available support from workstation vendor.
• Enhanced performance.
• Easy upgrades.
• Extremely low system latency and CPU overhead.
• Ability to power-up or down the VMEbus chassis without affecting the whole system.
• Easy migration to other platforms.

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